PROC. BIOL. SOC. WASH. 91(1), 1978, pp. 123-131 THE VOICE AND RELATIONSHIP OF THE TREEFROG HYLA HOBBSI (ANURA: HYLIDAE) William F. Pyburn Abstract. — The vocal signal of Hyla hobbsi consists of two types of calls: one call type is a single prolonged note with little frequency variation; the other is a frequency modulated three-note call. The two call types prob-ably have different functions. There are basic differences in call, color, and habitat between Hyla hobbsi and H. punctata, a species with which hobbsi has been confused. Introduction Cochran and Coin (1970) described the treefrog Hyla hobbsi from six specimens collected along Cano Guacaya, Amazonas, and the Rio Apaporis, Vaupes, Colombia. They called attention to the black dorsal spots, glandular dorsolateral folds and other structural features of the preserved frogs and concluded that Hyla hobbsi was not closely related to other known members of the genus Hyla. Duellman (1974) examined the holotype of H. hobbsi (MCZ 28052) and decided on the basis of mor-phological similarities that it was an example of Hyla punctata, a wide-spread and well-known neotropical species. Nonmorphological data were not given by these authors and apparently neither Cochran and Coin nor Duellman had seen live specimens of Hyla hobbsi. My objectives herein are to characterize the voice, habitat and habitus of Hyla hobbsi and to clarify its relationship with Hyla punctata. The voice recordings were made at night with a Uher 4000 Report L tape recorder at a tape speed of 19 cm/s and analyzed in the laboratory with a Key Elemetrics Sonagraph, model 6061 B. Voice In June 1973 J. K. Salser and I recorded calls (air temperature, 24.5 C) and collected 12 specimens of Hyla hobbsi on Wacara Creek, Vaupes, Colombia. The frogs called from widely separated shrubs along the stream and each shrub usually held only one frog. Perched over water, the frogs were reluctant to jump even when the shrubs were bumped by our canoes. Other specimens of H. hobbsi were brought to us from time to time by Caqua Indians, whose village is near Wacara Creek. The calls of Hyla hobbsi are given in long sequences interrupted by pauses of several seconds. A sequence usually consists of two types of calls (Fig. 1) : a plaintive whistle (type A) and a three-note call of variable
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